U.S. patent application number 11/212398 was filed with the patent office on 2006-03-02 for apparatus for extracting liquid crystal by heating under reduced pressure and method thereof.
Invention is credited to Hiroyuki Yajima.
Application Number | 20060044647 11/212398 |
Document ID | / |
Family ID | 35431108 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060044647 |
Kind Code |
A1 |
Yajima; Hiroyuki |
March 2, 2006 |
Apparatus for extracting liquid crystal by heating under reduced
pressure and method thereof
Abstract
An apparatus for extracting liquid crystal by heating under
reduced pressure includes a chamber defining an inner space in
which a waste liquid crystal panel is placed and having a heating
unit that heats the inner space, a pressure-reducing unit that
maintains the inner space under a pressure-reduced state, and a
heat conducting unit that heats and thereby weakens an
opening-sealing material or a sealing material of the waste liquid
crystal panel. The heat conducting unit is provided separately from
an inner wall of the chamber which generates a temperature for the
reduced pressure heat treatment in the inner space.
Inventors: |
Yajima; Hiroyuki;
(Matsumoto, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
35431108 |
Appl. No.: |
11/212398 |
Filed: |
August 26, 2005 |
Current U.S.
Class: |
359/361 |
Current CPC
Class: |
G02F 1/13 20130101; B01B
1/005 20130101; B09B 3/0058 20130101; B09B 3/0083 20130101 |
Class at
Publication: |
359/361 |
International
Class: |
F21V 9/06 20060101
F21V009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2004 |
JP |
2004-251494 |
Claims
1. An apparatus for extracting liquid crystal by heating under
reduced pressure, comprising: a chamber that has an inner wall and
a heating unit, the inner wall defining an inner space in which a
waste liquid crystal panel is placed, the heating unit heating the
inner wall to heat the inner space; a pressure-reducing unit that
maintains the inner space under a pressure-reduced state; and a
heat conducting unit that heats and thereby weakens an
opening-sealing material or a sealing material of the waste liquid
crystal panel, the heat conducting unit being provided separate
from the inner wall of the chamber.
2. The apparatus for extracting liquid crystal by heating under
reduced pressure according to claim 1, wherein the heat conducting
unit is a heat conductor which is connected to a heating source
which is separated from a heating source of the heating unit that
heats the inner wall of the chamber.
3. The apparatus for extracting liquid crystal by heating under
reduced pressure according to claim 1, wherein the heat conducting
unit is formed into a rod-shape such that, when a plurality of
waste liquid crystal panels are arranged, the heat conducting unit
can be brought into contact with opening-sealing materials or
sealing materials of the plurality of waste liquid crystal
panels.
4. The apparatus for extracting liquid crystal by heating under
reduced pressure according to claim 1, wherein the heat conducting
unit is formed into a rod-shape such that, when a plurality of
waste liquid crystal panels are arranged, the heat conducting unit
can be brought into contact with sealing materials of openings of
the waste liquid crystal panels, and at least a portion of a
sectional shape of the heat conducting unit conforms to an outer
surface of the sealing material of each opening.
5. The apparatus for extracting liquid crystal by heating under
reduced pressure according to claim 1, wherein the waste liquid
crystal panel is sealed without an opening, and at least a portion
of the opening-sealing material for sealing liquid crystal of the
waste liquid crystal panel is applied adjacent to a periphery of
the waste liquid crystal panel to easily receive heat from the heat
conducting unit.
6. A method of extracting liquid crystal by heating under reduced
pressure, comprising: disposing a waste liquid crystal panel in a
chamber which has a heating unit that heats an inner space defined
in the chamber by the medium of an inner wall of the chamber; and
weakening an opening-sealing material or a sealing material of the
waste liquid crystal panel using a heat conducting unit provided
separately from the inner wall of the chamber, when heating the
waste liquid crystal panel by the medium of the inner wall while
maintaining the inner space in a pressure-reduced state.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] The present invention relates to an apparatus for extracting
liquid crystal by heating under reduced pressure, to a method
thereof, and to a liquid crystal display device, and more
particularly, to an apparatus and a method which can extract liquid
crystal from liquid crystal panels to be disposed of from liquid
crystal panel manufacturing factories or liquid crystal panels used
in image display devices or information display devices disposed in
marketplaces, by heating under reduced pressure.
[0003] 2. Related Art
[0004] Recently, as the amount of domestic waste and industrial
waste has been increasing, there has been increasing demand for
means for rendering the waste harmless, in order to suppress the
increase in the amount of wastes and to prevent environmental
pollution caused by the waste.
[0005] In order to meet the demand, efforts have been made to
decrease the amount of waste by promoting recycling of industrial
waste disposed of from factories and domestic waste such as
electric home appliances, information devices or the like disposed
of from homes and offices.
[0006] In this regard, for example, liquid crystal panels are used
in electric home appliances and information devices. The number of
such liquid crystal panels in use is expected to increase rapidly
with the advancement of information technology society in terms of
the development of devices with low power consumption and slim
size.
[0007] Generally, a liquid crystal panel is structured in a manner
such that liquid crystal mainly consisting of organic solvents is
interposed between a pair of glass substrates on which transparent
electrodes such as ITO (indium tin oxide) are deposited, and
contacted surfaces of an outer periphery are sealed with an
epoxy-based adhesive. Polarizing plates are attached to the outer
surfaces of the glass substrates and organic materials such as a
color filter and so on are disposed inside the glass
substrates.
[0008] Apparatuses for recovering glass or rare metals from liquid
crystal panels have already been disclosed. An apparatus and a
method of processing waste liquid crystal panels in such a manner
that a waste liquid crystal panel is placed in a reaction furnace
without being broken, and subsequently heated in the reaction
furnace under a pressure-reduced state; thus, liquid crystal which
constitutes the waste liquid crystal panel and a portion of solid
organic materials which are disposed on the inner and outer
surfaces of the glass substrates are evaporated, and the remaining
portion of the solid organic materials are carbonized has been
proposed (for example, see Japanese Unexamined Patent Application
Publication No. 2004-230229).
[0009] Also, it is conceivable to provide a method of recovering
glass of a liquid crystal panel from a waste liquid crystal panel.
The method is composed of the steps of carbonizing organic
materials constituting the waste liquid crystal panel by disposing
the waste liquid crystal panel in a heating furnace without
breaking the waste liquid crystal panel, removing carbides from the
glass of the liquid crystal panel, removing inorganic constituents
from the glass of the liquid crystal panel by implementing a
cleaning process using a strong acid solution, and removing the
strong acid solution used in the process of removing the inorganic
constituents from the glass of the liquid crystal panel.
[0010] However, in the above-described methods, when the waste
liquid crystal panel is heated under a reduced pressure, it is
difficult to raise the temperature of the inside of the furnace and
the temperature of the liquid crystal panel being processed. In
order to extract liquid crystal from the liquid crystal panel by
heating under a reduced pressure which is similar to a vacuum
condition, it is necessary to break (weaken) a resin portion, but
the temperature for ensuring the breakage of the resin portion is
higher than the temperature for extracting liquid crystal. That is
to say, the temperature required for evaporating liquid crystal
under a pressure-reduced state is 150.degree. C., whereas a
temperature required for weakening the resin portion is 200 to
800.degree. C. Therefore, a temperature for implementing the
reduced pressure heat treatment must be set to a temperature as
high as from 200 to 800.degree. C. Consequently, as the processing
temperature is set to a high temperature in the range of 200 to
800.degree. C., the evaporated liquid crystal is likely to be
changed into harmful substances such as dioxins, PCB or the like,
which is not preferable from the viewpoint of safety.
SUMMARY
[0011] An advantage of the invention is that it provides an
apparatus for extracting liquid crystal by heating under reduced
pressure which can easily raise the temperature of a waste liquid
crystal panel and can lower the temperature of reduced pressure
heat treatment to as low as the evaporation temperature of liquid
crystal to efficiently recover liquid crystal with low energy
consumption and a method thereof.
[0012] An apparatus for extracting liquid crystal from a waste
liquid crystal panel by heating under reduced pressure according to
an aspect of the invention includes a chamber defining an inner
space in which a waste liquid crystal panel is placed and having a
heating unit that heats the inner space, a pressure-reducing unit
that maintains the inner space under a pressure-reduced state, and
a heat conducting unit provided separately from an inner wall of
the chamber which generates a temperature for the reduced pressure
heat treatment in the inner space, to heat and thereby weaken an
opening-sealing material or a sealing material of the waste liquid
crystal panel.
[0013] According to the structure, when extracting liquid crystal
from the waste liquid crystal panel placed in the chamber by
heating under reduced pressure, a temperature raise in the waste
liquid crystal panel for ensuring breakage (or weakening) of the
waste liquid crystal panel can be easily implemented, and a reduced
pressure heat treatment temperature can be lowered as low as an
evaporation temperature of liquid crystal. As a result, the liquid
crystal is unlikely to be changed into harmful substances and can
be recovered in a reliable manner. In this aspect of the invention,
as the waste liquid crystal panel is placed in the chamber to
undergo a closed processing by heating under reduced pressure
without the need of being broken, it is possible to safely recover
liquid crystal.
[0014] In the apparatus for extracting liquid crystal by heating
under reduced pressure according to another aspect of the
invention, the heat conducting unit is a heat conductor which is
connected to a heating source separate from a heating source of the
heating unit that heats the inner wall of the chamber.
[0015] According to the structure, not a heat conductor for
transferring heat of the inner wall of the chamber generated by the
heating unit constituting the chamber, but the heat conductor which
is connected to the separate heating source capable of being
independently controlled is provided. Therefore, since the
opening-sealing material or sealing material of the waste liquid
crystal panel can be directly heated and weakened, the surrounding
temperature in the chamber can be lowered as low as an evaporation
temperature of liquid crystal, by which it is possible to remove
the possibility of the extracted liquid crystal to be changed into
harmful substances.
[0016] In the apparatus for extracting liquid crystal by heating
under reduced pressure according to another aspect of the
invention, the heat conducting unit is formed into a rod-shape such
that, when a plurality of waste liquid crystal panels are arranged,
the heat conducting unit can be brought into contact with
opening-sealing materials or sealing materials of the plurality of
waste liquid crystal panels.
[0017] According to the structure, because the heat conducting unit
is formed into the rod-shape, when heating and weakening the waste
liquid crystal panel, the plurality of waste liquid crystal panels
can be placed on the rod-shaped heat conducting unit to undergo the
reduced pressure heat treatment.
[0018] In the apparatus for extracting liquid crystal by heating
under reduced pressure according to another aspect of the
invention, the heat conducting unit is formed into a rod-shape such
that, when a plurality of waste liquid crystal panels are arranged,
the heat conducting unit can be brought into contact with sealing
materials of openings of the waste liquid crystal panels, and at
least a portion of a sectional shape of the heat conducting unit
can conform to an outer surface of the sealing material of each
opening.
[0019] According to the structure, when weakening the sealing
materials of the openings of the waste liquid crystal panels, since
the heat conducting unit can conform to the outer surface of the
sealing material of each opening, heat transfer to the sealing
materials can be implemented in an efficient manner.
[0020] In the apparatus for extracting liquid crystal by heating
under reduced pressure according to another aspect of the
invention, the waste liquid crystal panel is sealed while not
having an opening, and at least a portion of the opening-sealing
material for sealing liquid crystal of the waste liquid crystal
panel is applied adjacent to a periphery of the waste liquid
crystal panel to easily receive heat from the heat conducting
unit.
[0021] According to the structure, even in the case of the waste
liquid crystal panel without an opening, since a portion of the
opening-sealing material for sealing liquid crystal can efficiently
receive heat from the heat conducting unit, it is possible to
effectively weaken the waste liquid crystal panel without an
opening.
[0022] A method of extracting liquid crystal from a waste liquid
crystal panel by heating under reduced pressure according to
another aspect of the invention includes the steps of disposing a
waste liquid crystal panel in a chamber which has a heating unit
that heats an inner space defined in the chamber by the medium of
an inner wall of the chamber, and weakening an opening-sealing
material or a sealing material of the waste liquid crystal panel
using a heat conducting unit provided separately from the inner
wall of the chamber, when heating the waste liquid crystal panel by
the medium of the inner wall while maintaining the inner space in a
pressure-reduced state.
[0023] According to the structure, when implementing reduced
pressure heat treatment, a temperature raise in the waste liquid
crystal panel can be easily implemented. Also, since a reduced
pressure heat treatment temperature can be lowered as low as an
evaporation temperature of liquid crystal, the liquid crystal is
not changed into harmful substances and can be safely
recovered.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements, and wherein:
[0025] FIG. 1 is a perspective view showing a chamber in an
apparatus for extracting liquid crystal by heating under reduced
pressure in accordance with a first embodiment of the
invention;
[0026] FIG. 2 is a perspective view in which a tray and heater
wires disposed in the chamber shown in FIG. 1 are partially
broken-out;
[0027] FIG. 3 is an explanatory view showing a state in which an
opening of an liquid crystal panel with an opening is heated by a
heater wire to cause leakage of liquid crystal;
[0028] FIG. 4 is of cross-sectional views showing sectional shapes
of the heater wire;
[0029] FIG. 5 is a view showing a portion which is likely to leak
when an opening-sealing material shown in FIG. 3 is heated by the
heater wire;
[0030] FIG. 6 is of views showing no-opening type liquid crystal
panels in an apparatus for extracting liquid crystal by heating
under reduced pressure in accordance with a second embodiment of
the invention;
[0031] FIG. 7 is an explanatory view showing one of the processes
for manufacturing the no-opening type liquid crystal panels shown
in FIG. 6;
[0032] FIG. 8 is a longitudinal cross-sectional view showing a
conventional liquid crystal panel;
[0033] FIG. 9 is of views showing an opened sealing type liquid
crystal panel; and
[0034] FIG. 10 is a view schematically illustrating a construction
of a system for processing liquid crystal of a waste liquid crystal
panel according to the invention.
DESCRIPTION OF THE EMBODIMENTS
[0035] Hereafter, the embodiments of the invention will be
described with reference to the accompanying drawings. First, a
typical waste liquid crystal panel 10 to be processed according to
the invention is illustrated in FIG. 8. The waste liquid crystal
panel 10 is one discharged from a liquid crystal panel
manufacturing factory or obtained from an image display device or
information display device whose lifetime has come to an end. The
waste liquid crystal panel 10 shown in FIG. 8 is an active type
liquid crystal panel such as a TFT liquid crystal panel. Of course,
it is to be readily understood that a passive type liquid crystal
panel can also be appropriately processed according to the
invention. The waste liquid crystal panel 10 has a pair of glass
substrates 1a and 1b which are separated from each other by a
predetermined distance. These glass substrates 1a and 1b are bonded
to each other with an sealing material 7 such as an epoxy resin or
the like which is applied along the peripheries of the glass
substrates 1a and 1b between the inner surfaces thereof.
[0036] The glass substrates 1a and 1b are properly separated by the
predetermined distance due to the presence of a spacer 8, and
liquid crystal 9 consisting of organic solvents is filled in the
space which is defined between the glass substrates 1a and 1b and
is sealed by the sealing material 7, thereby forming a liquid
crystal layer. Polarizing plates 2 are attached to the outer
surfaces of the glass substrates 1a and 1b with an adhesive. In one
glass substrate 1a, a polarizing plate 2 is disposed on the outer
surface, and a color filter 3, an overcoat 4 formed with a
transparent conductive layer 6, and an alignment layer 5 are
disposed on the inner surface. In the other glass substrate 1b, a
polarizing plate 2 is disposed on the outer surface, and a
transparent thin conductive film 6 and an alignment layer 5 are
disposed on the inner surface.
[0037] The polarizing plates 2, the color filter 3 and the
alignment layers 5 are formed of materials containing an organic
material as a main constituent, and the transparent thin conductive
film 6 is formed of a film containing an indium constituent or the
like. The reference numeral 11 designates a switching element which
is made of metal.
[0038] FIG. 9A shows the pair of glass substrates 1a and 1b, the
sealing material 7 for holding the liquid crystal 9 between the
glass substrates 1a and 1b, and an opening-sealing material 7b for
sealing an opening 7a defined in the sealing material 7, which
constitute the main part of the waste liquid crystal panel 10 shown
in FIG. 8. FIG. 9B is a cross-sectional view taken along the line
IXB-IXB of FIG. 9A, in which L1=0.5 mm and L2=5 to 10 .mu.m.
[0039] FIG. 10 is a view schematically illustrating construction of
a system for processing liquid crystal of a waste liquid crystal
panel according to the invention. The system includes a chamber 20,
a pressure-reducing pump 24, a capacitor 22, a decomposing device
23 and an activated charcoal filter 25. The chamber 20 defines an
inner space in which the waste liquid crystal panel 10 is disposed
and has a heating unit 21 for heating the inner space. The
pressure-reducing pump 24 is provided at the discharge side of the
chamber 20 and serves as the pressure-reducing means for reducing
the pressure in the chamber 20. The capacitor 22 is disposed
between the chamber 20 and the pressure-reducing pump 24. The
capacitor 22 condenses the liquid crystal which is evaporated and
thereby extracted by heating under reduced pressure of the waste
liquid crystal panel 10 in the chamber 20 to recover the liquid
crystal from other gases. The decomposing device 23 decomposes the
liquid crystal condensed and separated by the capacitor 22 to make
the liquid crystal harmless. The activated charcoal filter 25
cleans the remaining gas after the liquid crystal is separated from
other gases, and then discharges the gas.
First Embodiment
[0040] FIG. 1 is a perspective view showing the chamber in an
apparatus for extracting liquid crystal by heating under reduced
pressure in accordance with a first embodiment of the invention,
and FIG. 2 is a perspective view in which a tray and heater wires
disposed in the chamber shown in FIG. 1 are shown in a partially
cutaway fashion.
[0041] FIG. 1 shows the outer appearance of the chamber 20 in which
the reduced pressure heat treatment is implemented, in the
apparatus for extracting liquid crystal from the waste liquid
crystal panels 10 by heating under reduced pressure. The chamber 20
has a heating unit (not shown but indicated by the reference
numeral 21 in FIG. 10) which serves as heating means for
evaporating the liquid crystal from waste liquid crystal panels 10
placed in the inner space of the chamber 20. With the chamber 20
maintained in a pressure-reduced state by using the
pressure-reducing pump as pressure-reducing means, the chamber 20
heats the waste liquid crystal panels 10. A tray 28 for holding the
plurality of waste liquid crystal panels 10 and the heater wires 27
which serve as heat conducting means for locally heating the
opening-sealing material or the sealing material of each waste
liquid crystal panel 10 are disposed in the chamber 20.
[0042] The inner wall defining the inner space of the chamber 20 is
made of a metallic material which has an excellent heat
conductivity. The inner wall is heated by the heating unit
(indicated by the reference numeral 21 in FIG. 10) which is
disposed in the inner wall of the chamber 20, to serve as a main
heating source for evaporating the liquid crystal of the waste
liquid crystal panels 10. Accordingly, the inner wall of the
chamber is maintained at a temperature appropriate for the reduced
pressure heat treatment. The inner space of the chamber 20 in which
the reduced pressure heat treatment is implemented is reduced in
pressure to a value in the range of 0.01 to 10 Kpa. While a
processing temperature will be described later, in the embodiment
of the invention, the processing temperature can be set at about
150.degree. C. which corresponds to the evaporation temperature of
the liquid crystal.
[0043] The chamber 20 substantially has a box shape such as a
rectangular parallelepiped or a regular hexahedron. A cover which
can be opened and tightly closed is provided on the front surface
of the chamber 20. A heat-resistant glass is provided to the cover
so that the inner space of the chamber 20 can be observed. The
inner space of the chamber 20 is divided, for example, into two
upper and lower compartments. At least one tray 28 capable of
holding a predetermined number of waste liquid crystal panels 10
can be disposed in each compartment. The tray 28 is formed of an
insulating material having heat resistance and has the shape of a
frame or a basket.
[0044] FIG. 2 shows the tray 28 for receiving the waste liquid
crystal panels 10 and a structure which is disposed in the tray 28
to bring the opening 7a of the waste liquid crystal panels 10 into
contact with the heater wires 27 which are heat conductors.
[0045] Inside the tray 28, as shown by the two-dot chain lines E
and F in FIG. 2, partitioning plates or partitioning line members
are arranged in the longitudinal and transverse directions to hold
the waste liquid crystal panels 10 apart from one another. The
heater wires 27 serving as the heat conducting means are arranged
parallel to each other below the tray 28. Both ends of each heater
wire 27 pass through the inner wall of the chamber 20 and are
connected to a separate heating source 26 which is provided outside
the chamber 20 and is different from the heating unit.
[0046] The tray 28 is formed of an insulating material having a
heat resistance. The tray 28 has a structure capable of holding the
heater wires 27 inside the chamber. Both ends of the each heater
wire 27 pass through one side of the wall of the tray 28 to be
connected to the separate heating source 26 which is provided
outside (or inside) the chamber 20 and is different from the
heating unit. The set of the tray 28 and the heater-wires 27 may be
fixedly disposed in the chamber 20, or the heater wires 27 may be
detachably integrated with the tray 28 by providing connector means
on the inner wall of the chamber 20. When the tray 28 and the
heater wires 27 are detachably constructed, workability can be
improved when disposing the plurality of waste liquid crystal
panels 10 in the tray 28.
[0047] When disposing the waste liquid crystal panels 10 one by one
into the partitioned spaces of the tray 28 which has the frame or
basket-shaped configuration, each waste liquid crystal panel 10 is
inserted into each partitioned space with the opening-sealing
material 7b of the opening 7a (see FIG. 3 or FIG. 9) of the waste
liquid crystal panel 10 facing downward, so that the
opening-sealing material 7b of the waste liquid crystal panel 10
can be brought into contact with the outer peripheral surface of
the heater wire 27 which is disposed below the tray 28. The
opening-sealing material 7b is made of resin such as acryl resin,
and due to this fact, the opening-sealing material 7b has a
decomposition temperature which is lower than that of the sealing
material 7 formed of epoxy resin or the like.
[0048] As heat needed for heating is transferred to the heater
wires 27 through any heating source (the main heating source 21 or
the separate heating source 26), heat is directly transferred to
the opening-sealing materials 7b of the opening 7a of the waste
liquid crystal panels 10 respectively placed in the partitioned
spaces, whereby the opening-sealing materials 7b are heated. The
heater wire 27 may be formed of a wire rod which has a high
electric resistance so that a current can flow through the wire rod
for the purpose of heating the waste liquid crystal panel 10.
[0049] By heating only the sealed part of the waste liquid crystal
panel 10, the sealing resin is weakened and cracks are formed in
the sealing resin. As a consequence, leakage paths are formed in
the sealed portion as shown in FIG. 3, and the liquid crystal can
be evaporated into the inner space of the chamber 20 through the
leakage paths. The liquid crystal evaporated into the inner space
of the chamber 20 is condensed and separated by the capacitor 22
shown in FIG. 10 and then supplied to the decomposing device
23.
[0050] FIG. 3 shows a state in which the sealed portion of the
liquid crystal panel having the opening shown in FIG. 9 is heated
by the heater wire 27. Since the sealed portion is heated with the
heater wire 27 brought into contact only with the opening-sealing
material 7b, the temperature of the inner space of the chamber 20
is not significantly increased and corresponds to the evaporation
temperature of the liquid crystal. That is to say, by forming
cracks (causing leakage) in the sealed portion of the waste liquid
crystal panel 10 through local heating using the heater wire 27,
the liquid crystal filled between the glass substrates 1a and 1b
can be evaporated through the leakage paths.
[0051] FIG. 4 shows various sectional shapes of the heater wire for
heating the opening-sealing material 7b. FIG. 4A shows a sectional
shape of the heater wire 27' which has on the upper surface thereof
a curved portion to conform to the middle portion of the
opening-sealing material 7b having a curved contour. FIG. 4B shows
a sectional shape of the heater wire 271'' which has on the upper
surface thereof a curved portion and plane portions formed at both
sides of the curved portion to conform to the entire portion of the
opening-sealing material 7b having a curved contour and to extend
slightly beyond both widthwise ends of the curved opening-sealing
material 7b to thereby be brought into partial contact with the
glass substrates. FIG. 4C shows a sectional shape of the heater
wire 27''' which is rectangular or square and has a plane upper
surface. All these heater wires are formed to extend in the shape
of a rail so as to simultaneously heat the plurality of waste
liquid crystal panels.
[0052] Next, the workings of the first embodiment of the invention
will be described.
[0053] When assuming that the temperature of the inner wall of the
chamber 20 is T1, the evaporation temperature of the liquid crystal
is T0(=150.degree. C.), a heating temperature of the heater wire 27
is T2 and a decomposition temperature of the opening-sealing
material 7b under a pressure-reduced state is T3, the following
relation is established: T2>T3>T0. (1) Also, it is preferred
that the relation of T1=T0 be established.
[0054] As a method of increasing the temperature of the heater wire
27, the following A and B can be considered.
[0055] (A) A heating source for the heater wires 27 serving as heat
conductors is gained from the main heating source, that is, the
inner wall of the chamber 20 which is heated by the heating unit
21. In this case, the heating temperature T2 of the heater wires 27
is equal to the temperature T1 of the inner wall of the chamber 20,
thereby falling under the relation T2=T1. Thus, as can be readily
understood from the above relation (1), since the temperature T1
(which is equal to the heating temperature T2 of the heater wires
27) of the inner wall of the chamber 20 which is heated by the
heating unit (indicated by the reference numeral 21 in FIG. 10)
must be set to a temperature higher than the decomposition
temperature T3 (for example, 180.degree. C.) of the opening-sealing
material 7b including acryl resin, that is, in the range of 200 to
800.degree. C., when the opening-sealing material 7b is broken and
the liquid crystal is evaporated, the liquid crystal is likely to
be changed into harmful substances, which is not preferable from
the viewpoint of recycling and safety.
[0056] (B) A heating source for the heater wires 27 serving as heat
conductors is gained from the separate heating source 26. In this
case, the relation falls under T2.noteq.T1. Thus, since the heating
temperature T2 of the heater wires 27 is not related to the
temperature T1 of the inner wall of the chamber 20, the heating
temperature T2 of the heater wires 27 can be controlled by the
separate heating source 26 independently of the heating unit
(indicated by the reference numeral 21 in FIG. 10) which heats the
inner space of the chamber 20. Accordingly, the relation
T2>T3>T0 and the relation T1=T0 can be satisfied. As a
result, it is possible to set the temperatures as T0=150.degree.
C., T3=180.degree. C. and 200.degree.
C..ltoreq.T2.ltoreq.800.degree. C., and the temperature T1 of the
inner wall of the chamber 20 which is heated by the main heating
source can be set to satisfy the relation T1=T0(=150.degree. C.).
In other words, it is possible to set the processing temperature T1
in the inner space of the chamber 20 to a temperature (150.degree.
C. corresponding to the evaporation temperature of the liquid
crystal) which is lower than the range of 200 to 800.degree. C. set
in the above method (A). Therefore, it is possible to extract the
liquid crystal without changing it into harmful substances (such as
dioxins and PCB).
[0057] Accordingly, in the invention, as a method of raising the
temperature of the heater wires 27, the method (B) is adopted.
[0058] While it was described above that the opening-sealing
material 7b of the sealed portion of the waste liquid crystal panel
10 is locally heated by the heater wire 27 to be broken (weakened),
the invention is not limited to this case in which the sealed
portion is necessarily broken (weakened). Thus, the invention may
be constructed in such a manner that the sealing material 7 is
heated by a heat conductor (as shown by the two-dot chain line)
27a, 27b or 27c which is disposed around the periphery of the waste
liquid crystal panel 10, to be broken or weakened as shown in FIG.
3. Since the sealing material 7 is generally formed of epoxy-based
resin, when assuming that the decomposition temperature of the
sealing material 7 in the pressure-reduced state is T3', the
relationship between T3' and the decomposition temperature T3 of
the opening-sealing material 7b in the pressure-reduced state is
expressed by T3'>T3. Therefore, the heating temperature T2 of
the heater wires 27 by the separate heating source 26 is set to be
higher than the decomposition temperature T3' of the
opening-sealing material 7, to be expressed by T2>T3'. Even in
this case, the relation T2>T3'>T0 and the relation T1=T0 can
be satisfied.
[0059] In the case that, as shown in FIG. 3, the sealing material 7
is heated by the heat conductor (as shown by the two-dot chain
line) 27a, 27b or 27c which is disposed around the periphery of the
waste liquid crystal panel 10, to be broken or weakened, as can be
readily seen from FIG. 5, for example, the interface between the
glass substrate 1b and the sealing material 7 serves as a leakage
surface, from which the leakage path of the liquid crystal 9 is
formed.
[0060] According to the first embodiment of the invention, the
temperature of the waste liquid crystal panel can be easily raised,
and a processing temperature can be lowered. Also, due to the
closed processing in which the waste liquid crystal panel is placed
in the chamber 20 without being broken to undergo reduced pressure
heat treatment, it is possible to safely extract the liquid
crystal.
Second Embodiment
[0061] The above description set forth with reference to FIGS. 1 to
5 in accordance with the first embodiment of the invention falls
under an opened sealing type liquid crystal panel in which the
waste liquid crystal panel 10 has the opening 7a and the heater
wire 27 is brought into contact with the opening-sealing material
7b sealing the opening 7a to heat the opening-sealing material
7b.
[0062] However, the waste liquid crystal panels 10 may be
no-opening type liquid crystal panels which do not have openings.
In this type of liquid crystal panel, as shown in FIG. 6B, the
sealing material 7 is applied in the shape of a closed loop onto
one glass substrate 1a of the two glass substrates at a position
which is separated from the periphery of the glass substrate by a
predetermined distance, and then, an appropriate amount of liquid
crystal 9 is dropped onto the space surrounded by the sealing
material 7 using a dispenser (not shown). In this state, the other
glass substrate 1b is placed on the one glass substrate 1a so that
the one and the other glass substrates are bonded to each other by
the sealing material 7. Therefore, in the no-opening type liquid
crystal panels, the opening which is sealed by the opening-sealing
material 7b as shown in FIGS. 3 and 9 does not exist.
[0063] In this consideration, in this second embodiment of the
invention, in order to easily extract the liquid crystal from the
no-opening type waste liquid crystal panel, at least a portion of
the patterned shape of the sealing material 7 is applied to be more
adjacent to the periphery of the waste liquid crystal panel as
shown in FIG. 6A when compared with the conventional patterned
shape of the sealing material 7 as shown in FIG. 6B.
[0064] Namely, while the sealing material 7 is applied to the
liquid crystal panel in the shape of a frame to seal the liquid
crystal, at least a portion (indicated by the reference numeral 7c)
of the sealing material 7 is applied to project toward the
peripheries of the two glass substrates 1a and 1b which constitute
the liquid crystal panel. By means of this construction, in the
patterned shape of the sealing material 7 of the waste liquid
crystal panel shown in FIG. 6A, a heater wire 27 (shown by the
two-dot chain line) can be brought into contact with the outer
surface of the projecting portion 7c to locally heat and break
(weaken) the projecting portion 7c, so that the liquid crystal
filled in the space between the glass substrates 1a and 1b can be
extracted into the inner space of the chamber in which the reduced
pressure heat treatment is implemented. A plurality of projecting
portions 7c may be formed in the sealing material 7.
[0065] FIG. 7 is an explanatory view showing one of the processes
for manufacturing the no-opening type liquid crystal panels shown
in FIG. 6A. When manufacturing a plurality of no-opening type
liquid crystal panels, two large-sized glass substrates are
prepared, the sealing material 7 is applied onto one large-sized
glass substrate to form a plurality of sealing patterns each having
the projecting portion 7c so that the sealing patterns are arranged
in longitudinal and transverse directions in correspondence to a
plurality of liquid crystal panels to be manufactured. Then, the
other large-sized glass substrate is bonded to the one large-sized
glass substrate to obtain a mother substrate 30. Thereafter, the
mother substrate 30 is cut into the plurality of liquid crystal
panels using a dicing device.
[0066] Even in the second embodiment of the invention, similarly to
the first embodiment, since the liquid crystal can be extracted by
locally breaking (weakening) a portion of the waste liquid crystal
panel, in a state in which the temperature of the inner wall of the
chamber, that is, the temperature governing the inner space of the
chamber can be suppressed to about 150.degree. C. capable of
evaporating the liquid crystal, the liquid crystal can be
extracted. Accordingly, the possibility of the liquid crystal being
changed into harmful substances (such as dioxins and PCB) is
eliminated, and the liquid crystal can be extracted without being
changed into the harmful substances.
[0067] According to this second embodiment of the invention, even
in the case of the no-opening type waste liquid crystal panel, due
to the closed processing in which the waste liquid crystal panel is
placed in the chamber 20 without being broken to undergo reduced
pressure heat treatment, it is possible to safely extract the
liquid crystal.
[0068] As apparent from the above description, according to the
invention, advantages are provided in that, regardless of whether a
product adopts an opened sealing type liquid crystal panels or a
no-opening type liquid crystal panels, liquid crystal can be
extracted while preventing generation of harmful substances.
Therefore, safety and reliability are improved when extracting
liquid crystal. Further, the liquid crystal can be made harmless,
and a processing system having a high grade of safety can be
realized.
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